Door knob adapter



FIG. 1 is a top plan view of a door knob adapter showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is an end elevational view taken from the left of FIG. 1;

FIG. 6 is an end elevational view taken from the right of FIG. 1.

The ornamental design for a door knob adapter, substantially as shownand described.